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  Subjects -> CHEMISTRY (Total: 795 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (554 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (24 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (43 journals)
    - PHYSICAL CHEMISTRY (64 journals)

ANALYTICAL CHEMISTRY (47 journals)

Accounts of Chemical Research     Full-text available via subscription   (Followers: 243)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
Acta Analytica     Hybrid Journal   (Followers: 7)
Advances in Analytical Chemistry     Open Access   (Followers: 20)
American Journal of Analytical Chemistry     Open Access   (Followers: 27)
Analytica Chimica Acta     Hybrid Journal   (Followers: 33)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 28)
Analytical Chemistry     Full-text available via subscription   (Followers: 339)
Analytical Chemistry Insights     Open Access   (Followers: 17)
Analytical Letters     Hybrid Journal   (Followers: 10)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Biomonitoring     Open Access  
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 3)
Combinatorial Chemistry - an Online Journal     Open Access   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 5)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 25)
Current Analytical Chemistry     Hybrid Journal   (Followers: 6)
Drug Testing and Analysis     Hybrid Journal   (Followers: 5)
Electroanalysis     Hybrid Journal   (Followers: 4)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 6)
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription  
International Journal of Analytical Chemistry     Open Access   (Followers: 20)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 3)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 6)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 4)
ISRN Analytical Chemistry     Open Access   (Followers: 16)
ISRN Chromatography     Open Access   (Followers: 2)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 5)
Journal of Analytical Atomic Spectrometry     Full-text available via subscription   (Followers: 8)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 15)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 4)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 3)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 18)
Main Group Metal Chemistry     Full-text available via subscription   (Followers: 1)
Microchemical Journal     Hybrid Journal   (Followers: 3)
Phytochemical Analysis     Hybrid Journal   (Followers: 1)
Polish Journal of Chemical Technology     Open Access   (Followers: 2)
Reviews in Analytical Chemistry     Full-text available via subscription   (Followers: 8)
Surface and Interface Analysis     Hybrid Journal   (Followers: 14)
Techniques and Instrumentation in Analytical Chemistry     Full-text available via subscription   (Followers: 7)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 21)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 1)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 8)
World Journal of Analytical Chemistry     Open Access  
Journal Cover Journal of Analytical Chemistry
   [17 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1608-3199 - ISSN (Online) 1061-9348
     Published by Springer-Verlag Homepage  [2210 journals]   [SJR: 0.322]   [H-I: 17]
  • Determination of ibuprofen and paraben in pharmaceutical formulations
           using flow-injection and derivative spectrophotometry
    • Abstract: Abstract A flow-injection UV spectrophotometric method for the determination of ibuprofen in tablets was developed. The proposed method was achieved by using a flow cell which was located in a UV spectrophotometer and a peristaltic pump helped maintaining the carrier solvent, 0.1 M NaOH. During the study, flow rate, loop volume and the number of injections per hour were 15 mL/min, 193 μL and 100, respectively. The analytical signal of ibuprofen was linear in the concentration range of 400–1200 μg/mL. The detection limit and limit of quantification were determined as 27 and 91 μg/mL, respectively. Results for the determination of ibuprofen in tablets, 600 ± 2 mg/tablet (mean ± SD), were in good agreement with the labeled quantities, 600 mg/tablet. A relatively high recovery value, 100.4 ± 0.6%, proves the accuracy of the proposed method. The spectro-photometric method and reference HPLC method were shown to be comparable when Student’s t-test and Fisher test were applied to both methods. In addition, a fourth order derivative UV spectrophotometric method (at 268.8 nm and n = 9) for the determination of ibuprofen and a first order (at 271 nm and n = 1) derivative UV spectrophotometric method for the determination of paraben in pediatric syrups were developed. Recovery values for the determination of ibuprofen and paraben were 102.4 ± 1.1% and 100.2 ± 2.3%, respectively.
      PubDate: 2015-01-01
       
  • Simultaneous derivatization/pre-concentration of 3-phenoxybenzaldehyde as
           transformation product of permethrin with 2,4-dinitrophenylhydrazine by
           solid phase extraction and spectrophotometric detection
    • Abstract: Abstract A simple, cheap and sensitive solid phase extraction method has been described for simultaneous derivatization and preconcentration of 3-phenoxybenzaldehyde (3-pbAl) in aqueous samples. The method is based on the reaction of 3-pbAl with 2,4-dinitrophenylhydrazine (DNPH) to form 2,4-dinitrophenyhydrazone in a column packed with silica gel. Using 100 mg of the sorbent, this compound was sorbed at pH 3 and recovered with 4 mL acetonitrile prior to its spectrophotometric determination at 407 nm. The effect of DNPH concentration, pH, sample flow rate and volume, elution conditions and foreign ions has been investigated. A preconcentration factor of 25 was achieved by passing 100 mL of sample through the column. The relative standard deviation for 5 replicate analyses at three concentration levels of 3-pbAl was from 0.34 to 1.12%.The calibration curve was linear from 0.01 to 5 μg/mL of 3-pbAl, and limit of detection (S/N = 3) was 1.4 ng/mL. Molar absorptivity was found to be 4.7 × 104 L/(mol cm).
      PubDate: 2015-01-01
       
  • Highly selective solid phase extraction of mercury ion based on novel ion
           imprinted polymer and its application to water and fish samples
    • Abstract: Abstract A novel ion imprinted polymer (IIP) material has been synthesized for mercury ion. The IIP material is applied to the solid phase extraction (SPE) of Hg2+ from complex matrixes including water and fish samples. The IIP-SPE method is operated prior to cold vapor atomic absorption spectroscopy (CV-AAS) to determine mercury ion. In the polymer synthesis, mercury ion, 2-vinylpyridine, ethyleneglycol dimethacrylate and 2,2′-azobisisobutyronitrile are used as target, Hg2+ complexing reagent monomer, cross-linker and initiator, respectively. The polymer is characterized on the basis of FT-IR and thermal analysis (thermogravimetric, TGA; differential thermic, DTA; and differential scanning calorimetry, DSC). The obtained polymer block is ground, sieved and Hg2+ ions are removed from polymer particles by leaching with EDTA, which leaves a cavity in the polymer particles. The maximum Hg2+ adsorption capacity of IIP is 24.6 mg/g. Effective parameters on retaining Hg2+ such as pH, flow rate of sample and eluent, nature of the eluent, ionic strength, selectivity coefficient and retention capacity are investigated. The detection limit and the relative standard deviation are 5 × 10−4 ng/mL and 2.4%, respectively. After 20 adsorption cycles, the recovery of Hg2+ on IIP is only decreased by 3.2%. The column selective adsorption experiments of Na+, Cu2+, Pb2+, Cd2+, Ca2+ and Mg2+ ions with respect to mercury are conducted by using imprinted and non-imprinted polymer. These results showed that the IIP is highly selective for Hg2+ over the other metals.
      PubDate: 2015-01-01
       
  • Optimization of the conditions of phenol determination in natural and
           potable waters by HPLC with sorption preconcentration
    • Abstract: Abstract The conditions of the sorption preconcentration of phenols from samples of natural and potable waters in Diapak P concentrator cartridges filled with super-cross-linked polystyrene are optimized. Countercurrent desorption with acetonitrile or methanol ensures the elimination the step of organic solvent evaporation. The observed reduction of the sorption of humic and fulvic acids (HFA) on the addition of sodium sulfite to the samples of natural and potable waters prior to their processing probably relates to the change of pH. The preconcentration of phenols from natural and potable waters at pH 6–8 substantially reduces the sorption of HFA. The method is used to determine phenols in samples of tap water and water from the Yenisei river by the added-found method.
      PubDate: 2015-01-01
       
  • Specific features of the determination of arsenic in soils by
           electrothermal atomic absorption spectrometry with the injection of
           suspensions
    • Abstract: Abstract Problems of the determination of arsenic in soils by electrothermal atomic absorption with the injection of suspensions are discussed. To eliminate an exceptionally high rate of nonselective absorption due to intense evaporation of the inorganic matrix of the sample, the author proposed the reduction of the temperature to arsenic atomization. The optimized temperatures of pyrolysis and atomization steps are 500 and 1800°C, respectively; therein no matrix modifiers were used. The proposed approach was tested on reference samples of soils.
      PubDate: 2015-01-01
       
  • Simultaneous separation and purification of calycosin and formononetin
           from crude extract of Astragalus membranaceus Bge. var. mongholicus (Bge.)
           using high-speed counter-current chromatography
    • Abstract: Abstract A simple and effective high-speed counter-current chromatography (HSCCC) method for simultaneous separation and purification of calycosin and formononetin from the ethanolic crude extract of Astragalus membranaceus is described. HSCCC separation was performed using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (2.5: 2.5: 2: 3, v/v). A total of 7.5 mg calycosin and 11.2 mg formononetin was obtained from 500 mg crude extract of Astragalus membranaceus with purities of 98.5 and 98.3%, respectively, determined using HPLC. Chemical structures were confirmed by MS, 1HNMR.
      PubDate: 2015-01-01
       
  • New metalloporphyrazines as active components of membranes of
           anion-selective electrodes
    • Abstract: Abstract Nickel(II), manganese(III), and magnesium(II) porphyrazines are synthesized and investigated as active electrode components of polyvinyl chloride plasticized membranes for ion-selective electrodes (ISE). The potentiometric response of membranes based on metalloporphyrazines doped with 1,3-dihexadecylimidazolium chloride (ionic additive) relative to benzylpenicillin and iodide anions is studied. It is found that the introduction of the ionic additive significantly improves the electrochemical characteristics of the ISE: the slope of the electrode function in benzylpenicillinate solutions is (58 ± 7) mV/dec and c min = 7 × 10−5 M, and in iodide solutions, (55 ± 2) mV/dec and c min = 6 × 10−6 M. It is shown that the ISE based on manganese(III) porphyrazine with an ionic additive can be used to determine iodide in Iodinol preparation.
      PubDate: 2015-01-01
       
  • Enantioseparation of terbutaline by online concentration capillary
           electrophoresis coupling with partial filling technique
    • Abstract: Abstract A novel, simple and sensitive method for the enantioseparation of terbutaline enantiomers was developed using capillary zone electrophoresis (CZE) in combination with partial filling technique and field-amplified sample concentration. Under optimal conditions, the racemic terbutaline was resolved in less than 21 min by partially filling a fused-silica capillary with 15 mM β-cyclodextrin (β-CD, 1.9 psi, 90 s) and carrying out an electrophoresis with 50 mM phosphate buffer (pH 1.8) at 15 kV separation voltage. The sensitivity was further improved by using field-amplified sample injection (0.2 psi, 2.5 s water plug). Compared with conventional CZE, the resolution and sensitivity of two enantiomers were much improved (the detection limit decreased by 18–25-fold).
      PubDate: 2015-01-01
       
  • Solid phase extraction of thionine on agar as an adsorbent and
           spectrophotometric determination
    • Abstract: Abstract A new sensitive solid phase extraction procedure has been developed for the separation and determination of thionine by spectrophotometry. In this method thionine is retained by agar as an adsorbent in a mini-column, eluted by sulfuric acid-acetone mixture and its absorbance is measured at 600 nm. The effect of different parameters such as pH, eluent type and volume, flow rate, amount of adsorbent and volume of sample on the adsorption was investigated and optimum conditions were established. The calibration graph was linear in the range of 3–100 ng/mL of thionine in the initial solution with r = 0.9984. Limit of detection (LOD) based on 3s b was 0.9 ng/mL and the relative standard deviation (RSD) for 20 ng/mL of thionine was 2.9%. The method was applied to the determination of thionine in water samples.
      PubDate: 2015-01-01
       
  • Determination of the average molecular weight of hydroxyethyl starches by
           diffusion-ordered NMR spectroscopy
    • Abstract: Abstract A correlation equation is obtained for the evaluation of the average molecular weight (MW) of hydroxyethyl starches from the self-diffusion coefficient D measured using diffusion-ordered NMR spectroscopy. Correlation equations MW = cD −α are compared for hydroxyethyl starches, dextrans, and pullulans. It has been demonstrated that different MWs correspond to constant D values of uncharged polysaccharides with the similar type of nonvalent interactions and different degrees of branching.
      PubDate: 2015-01-01
       
  • Study on the electrocatalytic oxidation of Bisphenol A on Au
           nanoparticles/carbon nanotubes composite modified electrode
    • Abstract: Abstract A novel modified electrode, Au nanoparticles/multi-walled carbon nanotubes modified glassy carbon electrode (AuNPs/MWCNT/GCE) was fabricated in this work. In phosphate buffer solution (PBS-KCl), the electrochemical response of Bisphenol A (BPA) at this modified electrode was investigated by differential pulse voltammetry (DPV). A sensitive oxidation peak of BPA was observed at the potential of 0.396 V. Comparing with the bare glassy carbon electrode, the oxidation peak potential shifted to less positive potentials, and the peak current enhanced 10 fold. The factors of the electrochemical response of BPA, such as supporting medium, solution pH, and surfactant were carefully optimized. Under the optimum conditions, a linear calibration curve of the peak current of BPA and concentration was obtained in the range 8.0 × 10−8–1.0 × 10−5 M, and the detection limit was 3 × 10−9 M. The oxidation peak current increases proportionally with scanning speed, which suggests that the electrochemical oxidation of BPA is adsorption-controlled. The recoveries of this method are from 96 to 103.4%, indicating that the proposed method is accurate and reliable.
      PubDate: 2015-01-01
       
  • A procedure of ICP-AES analysis of silicon using microwave digestion and
           preconcentration
    • Abstract: Abstract A combined procedure has been developed for the analysis of high-purity silicon with preliminary vapor-phase digestion and preconcentration in a microwave oven using inductively coupled plasma atomic emission spectrometry (ICP-AES). Liners for high-pressure vessels of microwave oven ensuring the simultaneous distillation of matrices from 3–4 samples without their contact with the acid solution have been designed and manufactured. The procedure ensures the determination of up to 30 elements: Ag, Al, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hf, In, K, Li, Mn, Mo, Na, Nb, Ni, P, Rb, Sb, Sn, Sr, Ta, V, W, Zn, and Zr with the limits of detection 10−8 −10−6 wt %.
      PubDate: 2015-01-01
       
  • Methods for the detection and determination of singlet oxygen
    • Abstract: Abstract Methods for the detection of singlet oxygen in gaseous and liquid media are considered. Their advantages and shortcomings are discussed, including those in the quantitative determination of singlet oxygen.
      PubDate: 2015-01-01
       
  • Effect of temperature on the performance characteristics of continuous
           chromatomembrane gas extraction
    • Abstract: Abstract The effect of temperature on the analytical characteristics of the continuous chromatomembrane gas extraction of volatile organic compounds from aqueous solutions for their subsequent gas-chromatographic determination is studied theoretically and experimentally. It is found that an increase in temperature to 80°C lowers the detection limits of analytes by several times and significantly improves the performance of the gas-extraction system. The repeatability of the results does not depend on temperature when a water vapor condenser is used in the line of extraction gas.
      PubDate: 2015-01-01
       
  • Application of differential spectra from two different environments in
           simultaneous quantification of new fuchsine, crystal violet and malachite
           green in the presence of unmodeled interferents using first order
           multivariate calibration method
    • Abstract: Abstract This paper proposes the possibility of applying first order calibration methods for unknown sample(s) with unmodeled component(s) using the differential spectra obtained from subtracting of the absorbance spectra of sample that are recorded in two different environments. The main interest is that the method can be performed to quantify systems if the spectra of their unmodeled component(s) are the same in two different phases using first order calibration methods. The procedure demonstrates simultaneous determination of new fuchsine, crystal violet and malachite green in the presence of sunset yellow, tartarazine and amaranth as unmodeled interferences, whose spectra differ in aqueous and nonionic micellar solution of Triton X-100. The obtained satisfactory results indicate the successful applicability of the proposed method in complex samples.
      PubDate: 2015-01-01
       
  • Application of flat-sheet membrane extraction to determination of
           trihalomethanes in chlorinated drinking water
    • Abstract: Abstract Nonporous silicone flat-sheet membrane extraction with a cryofocusing (−30°C) sorbent interface coupled to gas chromatography-mass spectrometry was applied to the determination of trihalomethanes in chlorinated drinking water. The flow rates of the donor and acceptor phases in the membrane extraction module were optimized at 28–30°C to 1.5 and 55 mL/min, respectively. The methodology as established showed method detection limits of 0.2 μg/L or less, high-linearity calibration curves, and high accuracy and precision.
      PubDate: 2015-01-01
       
  • Nitrate detection activity of Cu particles deposited on pencil graphite by
           fast scan cyclic voltammetry
    • Abstract: Abstract Electrocatalytic nitrate reduction and sensing activities of Cu deposits from 0.01 M CuSO4 · 5H2O solution by fast scan (1000 mV/s) cyclic voltammetry on pencil graphite (PG) was investigated. The content of Cu particles on PG surface was controlled by fixing the deposition cycles between 0 and −300 mV. The performance of the different Cu/PG electrodes has been explained in terms of reduction current, kinetic order, exchange current density, specific electrical capacitance and nitrate sensing abilities. All these activities were modestly dependent on the content of Cu particles on the PG surface. The minimum catalytic sites on PG surface were generated even by the single Cu deposition cycle. Depending on the Cu content, the electrodes exhibited lowest nitrate detection limits in the range between 1.0 × 10−4 to 1.1 × 10−3 M. The nitrate detection performance of the Cu/PG electrode was justified with the ion chromatographic method.
      PubDate: 2015-01-01
       
  • Study of the acid-base properties of quercetin in aqueous solutions by
           color measurements
    • Abstract: Abstract Acid-base properties of quercetin in aqueous solutions are studied by the method chemical color measurements and dissociation constants (pK) are determined. The pK values are assigned to corresponding functional groups of quercetin and a probable scheme of their dissociation is proposed. A diagram of the distribution of ion-molecular forms of quercetin in the pH range 1–13 is built.
      PubDate: 2015-01-01
       
  • Ion-plasma treatment of reed switch contacts: A study by time-of-flight
           secondary ion mass spectrometry
    • Abstract: Abstract A TOF.SIMS-5 time-of-flight secondary ion mass spectrometer operating with pulsed 25-keV Bi+ ions for analysis and 2-keV Cs+ ions for sputter ion-beam etching was employed for studying the near-surface composition of iron-nickel (permalloy) contacts (blades) after the treatment in pulsed nitrogen plasma directly in hermetically sealed reed switches. The formation of 20- to 25-nm thick oxynitride coatings in the contacting region of the blades was observed. It was found that this coating was of the diffusive nature and produced via the plasma nitriding of the contacts.
      PubDate: 2014-12-01
       
  • Decomposition of multidimensional charge state distributions of ions
           produced by electrospray ionization of bioorganic compounds. Part 2:
           Testing the method for one-dimensional distributions
    • Abstract: Abstract Our earlier work was devoted to the further development of our method of the decomposition of the charge state distributions in ions of biopolymers with the aim to be able to assess the probability of their ionic groups to retain different charge carriers (protons, ions of alkali and other metals, etc.). This development was carried out with testing its different options on numerous simulated data. Some of these results are presented in this article. Testing a new method has shown its higher accuracy and, for a special case of a single type of charge carriers in comparison to the previously implemented method mainly at the expense of the implementation of new methods for averaging the results obtained. A number of calculations for experimental mass spectra of polyprotonated Cytochrome C molecules was made. The results apparently indicate changes in their both native and denaturated structures at different compositions of solution.
      PubDate: 2014-12-01
       
 
 
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